Trailer theft has become a major problem for the trucking industry. Truck drivers generally park their trailers at a loading area so that the trailers can be loaded with merchandise at a later time. In the interim, the trailers are left unattended. F.B.I. Federal Bureau of Investigation) reports for 1991 indicate that almost 100,000 trailers were stolen while parked at loading areas.
The most common method of stealing a parked trailer is for the thief to drive up to the trailer with his or her own tractor. The thief then connects the tractor to the trailer, including connecting the tractor's electrical line and air hoses to the trailer, activates the tractor's compressor to release the trailer's air brakes, and simply drives the tractor-trailer away. As a result, there is a need for an anti-theft device which can effectively prevent the theft of trailers and other vehicles which use air brakes.